Mythbusters crossbow

[cardinals08]

Any one here watch Mythbusters? Did you see the show the other night where they made the crossbow out of newspaper and underwear elastic? I started to make a mini crossbow out of pencils and a rubber band to shoot throwing darts or small pencils to see what it could do. I got it so it could shoot stuff, I shot a battery against my pillow, and a pen against my door within 5 feet, the pen had already turned sideways. I gotta find a better way to stabilize ammo, and I want to add a firing mechanism but dont know how to go about making one
this is what I got so far
its nothing much, just thought I could get some improvement suggestions

[Copperboy]

I think making the actual bow bending istead of the string would provide more power. Here's a cool site about crossbows (it's in swedish but you could at least look at the pictures ) with many interesting designs...to bad they are pretty much illegal in more powerful setups.

[darkpyro]

wheres the site

[regre7]

I think that using a projectile with stabilizing fins would help improve your accuracy/getting it there-ness.

[Copperboy]

Haha, oh f**k! I've made that mistake twice now http://www.armbagen.nu/armborst/
SORRY!!!!!!

[jrblast]

I think that using a projectile with stabilizing fins would help improve your accuracy/getting it there-ness.

Or even if it were just flat, that way theres more resistance when it wants to turn (Wow, first post in many months o.O)

[PaRaSiTe]

I've seen nearly all the Mythbusters

Except that one

[Brian the brain]

Build a decent one for crying out loud!!

Rubber bands ARE more powerful ( when u use like 40 at a time) than any homemade bow I can tell you.

I've made my first crossbow when I was 12.Pretty powerful but eventually the bow broke.( damned wood!!) I made the front end longer so I could use the "gun" to shoot rubber bands( they stretch a lot further).Didn't take me long to discover that if I could shoot a rubber band, I could also place a rock onto it and shoot that.Or an arrow for that matter.
Ofcourse....12 rubber bands worked even better...It turned into a lethal weapon from there.Loading like this was tedious but as a 12 year old I could "up" the power by adding bands without the effort of pulling a heavy bow at once .(Stretching every band seperately takes little effort)

I later designed a marble gun with 40 rubber bands that worked with pulleys.Doubling the distance of the"string", but not of the rubber bands.Pulling the string required only half the force needed to pull the bands themselves so I just doubled the amount of bands!This way the gun was loaded in one pull.

That made the "string"contract at twice the speed of the bands aswell getting a marble to very...very high velocity.I put a marble half way into a solid wood door.An arrow would have been almost TOO dangerous( but that would be simpler to build and aim).The marble gun was silent except for a "click"( marble disappeared into the sky in a straight line!!)
Some pictures are here:
http://devinexecution.com/airpower2/det ... ode=search
trigger mechanism:

http://devinexecution.com/airpower2/det ... ode=search
Repeated shooting of marbles could be possible with a magazine.

If anyone is interested in building a "pulley gun" I'll help U with drawings when needed all the way.
It's my invention so I take great pride in it.To shoot marbles you need two rails to form a "barrel" like so; [0] but turned on it's side.The string slides between them.

[Copperboy]

Your trigger mechanism is similar to the ones on my crossbow. How to you cock it? Do you just draw the string back "outside" the stock? Where the string hits the marble, is it some sort of wadding or reinforcement? Like it alot, somethimes mechanical raw-force is cooler than pneumatic Reminds me of a pellet bow : http://www.adrax.com/watsons/stonebow.htm nice work!

[Brian the brain]

The string can't leave the slot between the aluminium strips.The "catch"can be rotated back,so the string can pass it in a backward motion but when the trigger is not pulled it can't rotate forward.( with help of a spring it returns to its position)
So when you pull the spring back you hit the catch, when you pull back further you'll hear a click and the string is secured.
I did use wadding on the tring because the strips could bend a little so the string sometimes bypassed the marble.
The marble did'nt roll out easily by itself.

The bigger you build this the easier it should be.
1"marbles should make this a formidable weapon.

[cardinals08]

I was thinking of making a bow exactly (well almost exactly, I didnt think of pullies) when I made my pencil thing. I was going to build a decent one but the pencil thing was just a project to put together in a couple minutes.

[Copperboy]

By the way, Mythbusters rule Cardinal, you mean like a standard bow? Brian, the pulleys, are they the kind you have on a boat? And what sort of rubber-band is that?

[Brian the brain]

I found the pulleys at a Dutch hardware store in a metal housing.I sawed off the metal housing so I could use them.The rubber bands I used are used by the dutch postal services.THey bind stacks of letters together with them and toss em on the street when they're finished with them.Offices usually have boxes full of them.A general purpose item.
It's made of natural rubber.The best there is!!
You could use surgical tubing as well.
Just about anything made of natural rubber

condoms might be an exeption to this....

[urbana]

i used a peice small pvc pipe for the flexy part and nilon string, super powerfull!!!!!

[Benny]

pvc pipe doesnt bend very well..... it fragments.